Disk drive system and control circuitry adapted for downward compatibility

Abstract

A higher-capacity disk drive system and a higher-capacity removable disk cartridge adapted for downward compatibility with older, lower-capacity disk drive systems, wherein a unique control information format is stored on higher-capacity removable disk cartridges to distinguish them from older, lower-capacity removable disk cartridges and thereby to facilitate cartridge capacity recognition by the higher-capacity disk drive system. Upon recognizing the capacity of an inserted removable disk cartridge, the higher-capacity disk drive system can read and write data to the removable disk cartridge such that data which it stores on a lower-capacity removable disk cartridge may be read by lower-capacity disk drive systems.

What is claimed is:  
     
       1. An apparatus for identifying the data storage capacity of a particular removable disk cartridge inserted into a removable cartridge disk drive system, said apparatus comprising 
       a first read/write channel connected to first circuit means for identifying an embedded servo pattern associated with a first removable disk cartridge having a first defined storage capacity when said first removable disk cartridge is inserted into said removable cartridge disk drive system, and  
       a second read/write channel connected to second circuit means for identifying an embedded servo patterns respectively associated with a removable disk cartridges having second and third defined storage capacities when one of said second and third removable disk cartridges is inserted into said removable cartridge disk drive system.  
     
     
       2. A disk drive adapted to receive a removable disk cartridge including a magnetic disk having a plurality of tracks divided into a sector pattern such that the sector pattern divides each track into a plurality of sector portions of substantially equal arc length, the magnetic disk also including a servo burst with each sector portion of each track, comprising: 
       means for rotating the magnetic disk;  
       means for detecting a plurality of servo bursts on the magnetic disk;  
       means for measuring the time between detected servo bursts;  
       means for comparing the measured time to an expected time associated with a particular disk capacity;  
       means for detecting the track number of the track being read;  
       means for validating the detected track number; and  
       means for identifying the capacity of the removable disk cartridge based on the measured time between detected servo bursts and on the validation of the detected track number.  
     
     
       3. The disk drive of claim  2 , further comprising: 
       a plurality of read/write channels each associated with a removable disk cartridge having a particular storage capacity;  
       means for selecting a read/write channel based on the identified capacity of the removable disk cartridge; and  
       means for performing read and write operations on the removable disk cartridge using the selected read/write channel.